Block copolymers represent an important class of materials, which have received widespread attention because of their remarkable micro-and nanophase morphology. This morphology leads to unique properties compared to homopolymers or their blends. Classical examples of block-copolymer morphology are lamellae, hexagonal-packed cylinders and body-centered-cubic arrays of spheres. [1] During the last decades, important advances have been made in the synthesis, characterization, and application of block copolymers. In particular, anionic polymerization has been successfully applied in their controlled synthesis. [2] Several other routes have been realized as well, for example, controlled radical polymerization, [3] cationic polymerization, [4] group transfer, [5] and metathesis, [6] or combinations of such techniques. Nevertheless, block-copolymer synthesis remains a challenge for certain materials and several interesting combinations could not be realized to date. On the other hand, recent developments in the field of supramolecular chemistry have shown that small (self-)complementary building blocks can lead, through self-organization processes, to large, well-defined structures, which are held together by noncovalent interactions such as hydrogen bonds [7] and metal-to-ligand coordination. [8] Herein we present a new highly controlled and welldefined construction principle for block copolymers that utilize supramolecular interactions, in this case metal-toligand coordination. By this method new combinations of block copolymers can be prepared, which are not accessible, or have been very difficult to access to date. This allows a comparison of the new metallo-supramolecular compounds with classical well-documented covalent block copolymers. For this purpose we chose the terpyridine ligand as the central building unit, which is well-known for its outstanding ability to form stable bis complexes with a large variety of transitionmetal ions (Figure 1). [9] The main advantage of having a metal complex as the bridging unit is the possibility of cleavage at this junction point. Therefore new ™smart materials∫ are accessible. Moreover, the metal ion being at the interface between the blocks may cause additional interesting features regarding morphology, thermal and mechanical as well as photophysical properties.The construction of the supramolecular block copolymers works along the same principle as their covalent counterparts.

An amphiphilic metallo-supramolecular polystyrene-block-poly(ethylene oxide) diblock copolymer containing a bis(2,2‘:6‘,2‘ ‘-terpyridine)ruthenium(II) complex (PS20-[Ru]-PEO70) as a supramolecular connection between the two constituting blocks has been compared to the covalently bonded counterpart (PS22-b-PEO70). The two different copolymers have been used to prepare kinetically frozen aqueous micelles that consist of a glassy polystyrene core surrounded by a poly(ethylene oxide) corona. The micelles have been characterized by dynamic light scattering (DLS). In the case of the PS22-b-PEO70 copolymer, micelles with a hydrodynamic diameter (D h) of 18 nm are observed while stable micelles with a D h of 65 nm and larger aggregates are formed for the PS20-[Ru]-PEO70 sample. Addition of different salts during the initial stage of micelle formation has a deep effect on the final micellar characteristic features, which are now similar to the ones of the covalent system. This effect is attributed to a decreased electrostatic repulsion between the charged bis(2,2‘:6‘,2‘ ‘-terpyridine)ruthenium(II) complexes which are present at the interface between the immiscible polystyrene and poly(ethylene oxide) blocks. Furthermore, addition of different salts to solutions of the PS20-[Ru]-PEO70 micelles, initially prepared in the absence of salt, caused a decrease of their size, although the packing of the charged bis(2,2‘:6‘,2‘ ‘-terpyridine)ruthenium(II) complexes could not be changed in these kinetically frozen micelles. A decrease in micelle size has also been observed as temperature increases. These effects have not been observed in the covalently connected counterpart and are thought to originate from stretched poly(ethylene oxide) chain segments. A model for metallo-supramolecular micelles is tentatively proposed that takes into account the experimental observations.